The invention relates to armored piping systems, and in particular to a protective end covering adapted to mate with a pipe coupler, which covering retains the pipe end within the coupling and prevents separation of the pipe from the coupler in the event of a pipe failure near the mated connection.
Prior art armored piping systems, one of which is illustrated in FIG. 1, generally consist of a beaded glass pipe 10, having a beaded end portion 13 and a circumferential coupler 17 which engages in a mating relationship with the beaded end 13 for coupling the first mentioned pipe section 10 with another pipe section 10' having a similar beaded end 13'. The beaded pipe 10 has a spirally wound circumferential armor 12 covering a main pipe section 14 of pipe 10.
In the piping system described in FIG. 1 the armor coating 12 does not normally extend from one end of the pipe 10 to the other, but more specifically, the armor coating 12 is terminated at some point 16 just rearward of the bead portion 13. The reason for termination of the armor 12 is for the purpose of protecting the armor 12 from the wicking or leakage of corrosives which might be flowing in the pipe system. A gasket seal 15, enclosed within the coupling 17, mates with the beaded end 13 and forms a tight circumferential seal thereabout. By terminating the armor 12 in the vicinity of the rear of the bead at 16, the seal made with the beaded end 13 is rendered satisfactory and the external armor 12 is protected from corrosives.
Many of the armored piping systems described herein are fabricated from glass tubing forming the pipe 10 of normally constant lengthwise wall thickness t for the main pipe section 14 rearward of the bead 13. When the bead 13 is fabricated, by conventional means, the thickness of the wall of pipe 10 in the vicinity of the bead 13 increases as illustrated. It is known that stress concentrations in glass tend to predominate in areas of dimensional change. Thus in FIG. 1 stress concentrations tend to accumulate in the area 16 just rearward of the bead 13.
If the pipe 10 fails in the area 16 rearward of the bead 13, the pipe may slip transversely out of the coupler 17 possibly causing substantial injury to personnel and damage to surrounding equipment.
The need for a more effective pipe coupling system with failure resistance is therefore apparent from the shortcomings of the described prior arrangement.